IMAGE PROCESSING DEVICE AND ITS MEASUREMENT ITEM INSPECTION METHOD

PROBLEM TO BE SOLVED: To detect a correct edge position even in the case where the surface state of an inspection object is no good or the lighting in an inspection environment is not uniform. SOLUTION: Previously, a threshold value for temporary measurement and a threshold value for real measurement are set based on a model image. At an inspection execution time, an image signal formed by picking up an inspection object is input to an I/O interface portion 14 and is stored in a memory 12. A CPU 11 conducts processing for measuring the measurement items of the inspection object. First of all, the luminance value profile of an inspection object image is formed by the image signal stored in the memory 12. Next, a temporary edge position coinciding with the temporary measuring threshold value is detected on the profile, and based on this the profile is divided into plural measurement ranges. Edge positions coinciding with the real measuring threshold value are detected for the respective measurement ranges. When plural edge positions are detected in one measurement range, the edge position closest to the temporary edge position is selected.